class Container {
    static of(value) {
        return new Container(value);
    }

    constructor (value) {
        this._value = value;
    }

    map (fn) {
        return Container.of(fn(this._value))
    }
}

class Maybe {
    static of(x) {
        return new Maybe(x);
    }

    constructor (x) {
        this._value = x;
    }

    isNothing () {
        return this._value === null || this._value === undefined;
    }

    map (fn) {
        return this.isNothing() ? this : Maybe.of(fn(this._value))
    }
}

module.exports = {
    Container, 
    Maybe
}